Notes: This fungus was a little surprise I took it to be Entoloma out in the field till I saw the gills. Cap is very thin 2 mm at most as are the gills with cross walls at a lower level. Spore seam to be white but still working on this Update.. spore print has formed showing white smooth spores 8×4 um, Boletus like in shape. The pileipellis hyphae are incrusted.

This observation was labeled as ‘Rhodocybe “Waiora”’ which was synonymized with the genus ‘Rhodocybe’. From the dialog I get the impression that this is an unpublished species, but I’m not clear is “Waiora” is a vernacular or a provisional name. I’m leaving a note here in the observation so searches for ‘Waiora’ continue to return this observation.

Has some beautiful mushrooms. I was very surprised to finally understand how obscure this section in science is. NZ and Australia are both places I would love to go and hunt. From discussions here on MO, I see how badly needed more study is!

Agree with Debbie that this is probably the Rhodocollybia (unpubl. sp.) frequently found in NZ, but heavily infected by a parasite. I posted a picture of it recently on Mike Wallace’s thread, but don’t know how to refer to it further.

Debbie
I find it quite frustrating that NZ has so many fungi that are not named, even groups that have been well document its not to difficult to find un described species from with in such groups. Added to this we have no field guides available!!

if this is the Rhodocollybia sp. “Wairora,” then it would have a dextrinoid layer in the spores.

Neither of the two mushroom descriptions linked to by Noah mention the encrusted hyphae. and those gills…! I commonly see a Lactarius species in Northern CA that has gills just like these…more like they are changing to a secotioid form rather than being parasitized…but more questions than answers with this curious and spectacular fungus!

Man, no fair posting these NZ sightings…they put our boring old North American species to shame!

Spore colour and shape fits a lot in that family (Mycena, Clitocybe, Lyophyllum etc., but I have never seen anything like this. Laccaria, with spiny spores, is out of the question. The distortion of the gills can be a result of some parasite – or maybe not..?

To clarify, my last comment was not an argument for Entoloma. It was in consideration of whether the mushroom might be parasitized.

For some (dumb) reason, I only now noticed the location of this find. I’ve seen some very unique fungi from NZ and AU, so I would not be surprised if this is something very different that I am not familiar with.

What a bizarre combination of characters. If the spores are boletus-shaped, then I agree with Clive that Entoloma is out of the question. Also, the lamellae may have been parasitized, but also look like they were rather veiny/intervenose/contorted to begin with.

I imagine it would depend on where you sectioned the tissue. For instance, it looks like the part of the gills nearest the bottom of the photo is more fully consumed by mycelium than the opposite side. If your section was from a part that was not fully colonized, then you might still see basidia.
To confirm, take a section from the area that looks well colonized and see if you can find any asci.
If you cannot find any asci, then I guess this is something different altogether, as you suspect.

Oh, also- the gills look considerably deformed, but I’m guessing that this is a result of the parasitism. I’ve seen some partially colonized, yet rather malformed mushroom fruiting bodies.